Thread: Want your DC checked for invisible dust?

Just a heads up on particle counters. I received an email the other day telling me that Clearvue in the US will be selling Dylos particle counters so I will, be able to stock them as well. As yet no pricing or stock but I will let you know those details when I can.


Air Quality Monitor $199

Originally Posted by Chris Parks

Just a heads up on particle counters. I received an email the other day telling me that Clearvue in the US will be selling Dylos particle counters so I will, be able to stock them as well. As yet no pricing or stock but I will let you know those details when I can.


Air Quality Monitor $199

Chris, Maybe you should make this a separate post in Announcements as I'm sure a lot of people would be interested in this.

Bob,

Maybe it's just my browser but your pic's didn't display.

Originally Posted by BobL

BTW - The problems with VC3 have been improved but not as much as I had hoped, by a filter replacement.


VC2 is used inside a router table/cabinet (See Diag below) and connected to the router chamber by a short length of VC hose.

Originally Posted by Breezy

Bob,

Maybe it's just my browser but your pic's didn't display.

Yeah - they have gone for me too.
They have also been deleted from my attachments list

I'd edit them back into the post but its is too late so here they are again.

Now that I'm retired I have more time to get back to doing some dust testing.

Today I tested a DC with a PF, and a high end VC connected to a small cyclone (SC).

The DC had a number of leaks in the plastic bag and around the rim of the DC housing.
This probably explains why the PF is not working quite so well a other PFs I have measured.
Just a reminder that negative efficiencies (shown in %) mean the device is making more dust than it is collecting.
The result for the VC alone is typical of most (even expensive) VCs - ie making more of the finer dust than they collect.




The interesting thing for me was the effect of the SC.
While it improved the efficiency of the collection of dust above 5 microns it generated more dust for all of the other sizes and especially so for the two smallest particle size ranges. In addition these devices reduce flow so fewer fine particles are grabbed at source.

BobL,

Took a look at the Dylos particle counter. It seems to measure only two sizes of particles.

You, on the other hand, have readings of a range of sizes.

What kind of instrument are you using?

I'm have been using ARTI and a Met 1 particle counters.
Both have 6 particle size ranges and they cost about 5 grand in Australia

The dylos units have 2 ranges they say cover moulds (>0.5 microns ) and pollen (>2.5 microns)
To perform accurate determinations of dust loadings per unit volume you really need a 5 and preferably 10 micron discrimination.
To understand what is happening the finest particle space it is handy to have 0.3 and 0.5 micron discrimination.
Hence a minimum number of channels I would work with is 4.

The dylos units are more than adequate for detecting leaks in systems and getting a general picture of what is going on inside a . But 95% of the leaks I see one does not need a particle counter for. Today I could see two leaks on the seal between the plastic bag and the DC and two holes in the side of the bag. I find it hard to believe that there are so many leaks in systems

One problem with the Dylos is that they do not provide sampling volume value - all they say is the sampling volume is equivalent of a 12 year old resting breath but they do not say what this volume is. The reason for this is probably because to perform accurate volume readings the pumps need to be calibrated about every year. Uncalibrated pump volumes means the counts reported are OK for relative work - ie compare readings made by the same unit but readings on different units cannot be accurately compared, and neither can any reading be converted to mg of dust per cubic m of air to establish OHS dust values.

Despite I think this they would be worthwhile gizmo for say a mens shed. I have seen a few people buying these and reporting their use in Blogs that demonstrates they have no effin clue about what they are doing. For example they get very high readings in their home and lower readings in their shed so they reckon their sheds are OK. The BIG difference of course is that their home is full of skin, hair, combustion products, and fabric dust - which most humans have been living with for hundreds of thousands of years, but their shed is full of wood dust - there is a big difference.

Yesterday I tested a brand new type industrial DC.
3 Phase 5.5HP,
Pleated filter with 20 m^3 surface area (equivalent to about 3 regular cylindrical PF).
400 L chip collection with forced positive pressure sealing of bags
<0.1 mg/m^3 dust emissions.
The owner is a hobby woodworker who owns a 170m^2 factory unit to house his high quality machinery.
Even though it is an industrial location he cannot vent outside.

The DC is fully ducted to 10 machines (TS, 2 x BSander, 2 x BandS, Jointer, Thicknesser, Downdraft table, router table a SCMS) using a mix of 8,6 and 4" metal ducting.
The ducting cost about twice the cost of the DC.

Although I did not measure the flow rates, they are mostly very high so I guess it will have excellent capture at source.
While it easily meets it's rated 0.1 mg/m^3 specs, in terms of fine dust filtering the filter performed slightly below the average of the 12 PFs I have measured thus far.
I suspect it will perform better once the pleated filter is conditioned and being ruggedly built should be less susceptible to leakage issues.

A Clearvue and PVC ducting would have been IMHO been a MUCH better choice

Will this be tested again after some use? I hate filters, they are a band aid solution at best and it is my gut feeling that the area of filter calculated to do the job should be doubled on any installation to slow down the air and debris hitting the filters. I would go to extreme measures to eliminate their use on any installation given the choice.

I envy this guy's workshop ... but am glad I don't have filters ... the other benefit for which I am forever grateful is the small footprint of the Clear Vue.

Originally Posted by Chris Parks

Will this be tested again after some use?

I hate filters, they are a band aid solution at best and it is my gut feeling that the area of filter calculated to do the job should be doubled on any installation to slow down the air and debris hitting the filters. I would go to extreme measures to eliminate their use on any installation given the choice.

I agree for woodworking situations. But i'm not that fussed by filters having worked with them and maintained them all my working life. There's also currently no other way to get ultimate filtration levels.

Avoid the need for filtration is my answer. dealing with wood dust this is possible other media can present problems but I don't deal with that apart from one instance and that is outside the reference of this forum.

This has been an interesting thread. I hope BobL keeps posting.

As an aside, I now feel much better about the central vacuum system I installed in the house during renovations!
The hose takes up as much room as a normal vac and can be quite unwieldy.
However, the central unit is located behind the garage, so any leaks are well away from the living area.